My $.02 from back when I worked on Wayfarer Foothills (the norn starter map)

Norn are kind of jerks. Yes, dredge are xenophobic and hostile to outsiders (at least the military ranks are openly hostile, dredge miners just want to work), but the norn delight in provoking other species (dredge, grawl, jotun, et al) and displaying their superiority.